Notes. 
160 
region on which the sporangia are situated. The tissue underlying 
the sporangia, however, presents peculiarities in structure which may 
modify this conclusion to some extent. Beneath the single sporangia 
developed on the edge of the prothallus a few tracheides, which agree 
in every respect with those present in apogamous prothalli, were 
always to be found. Similar elements were always present in the 
tissue beneath the groups situated on the process. It is possible that 
here, as in the case of the sporangia upon the prothallus edge, the 
first tracheides are developed before the young sporangium can be 
recognized. All that can be stated with certainty is that they are 
already present beneath very young sporangia. The tracheides may 
become connected together into a band, resembling a rudimentary 
vascular bundle, and suggesting a comparison with the vascular supply 
of a sorus. 
The development of the sporangium could not be followed in detail 
in the material obtained as yet, but a sufficient number of stages have 
been found to make it clear that there is no difference of importance 
from the well-known course of development of the same member on 
the sporophyte. In the youngest stage seen, the apex of the sporan- 
gium was occupied by a tetrahedral cell, the cells destined to form the 
lateral portions of the wall having already been cut off from a large, 
dome-shaped terminal cell, the limits of which were clearly recogniz- 
able. This was borne upon a stalk cell. A tetrahedral archesporium 
is formed, from which tapetal cells are cut off. The tapetum subse- 
quently becomes two-layered, and the central cell develops into 
a group of sporogenous cells. From these, in the most mature 
sporangia found, a number of dark brown spores had developed, while 
the tapetum was represented by numerous granules between the 
spores. The number of spores appeared to be the same as was 
contained in a sporangium developed on the sporophyte. The 
sporangium wall was perfectly developed ; the cells of the annulus 
showed the characteristic thickening of their walls, which were of 
a dark brown colour, and a well-formed stomium was present. When 
tested with dehydrating agents, the mechanism of the annulus was 
found to be perfect. The stalk consisted of four rows of cells. 
No sporangia have been found in which the spores were ripe, but 
in view of the advanced stage of development in those observed, there 
is every probability that some may be obtained. It will be interesting 
to ascertain if the spores are capable of germination, and if the 
